Many processes and/or applications in the field of communication technology such as person-to-person applications are interactive. These interactive processes and/or applications not only care about the one-way delay but also the round-trip delay, such as SIP call control signaling to initiate a session, or Push-to-Talk services over cellular networks. If the round-trip delay of an interactive application is too high, the end user will probably become unsatisfied and quit the application. Therefore it is very important to be able to guarantee or at least reduce the round-trip delay for interactive processes and applications.
In modern communication systems such as packet based wireless systems, like High Speed Packet Access (HSPA) or Long Term Evolution (LTE) systems, there are no special techniques to handle the round-trip delay requirement but just the one-way delay requirement. To guarantee the one-way delay, the scheduler generally gives higher priority to delay-sensitive traffic. In many communication systems, such as HSPA and LTE, scheduling of users is performed from the network side. Since the round-trip delay is composed of two one-way delays, it is viable to guarantee the round-trip delay by guaranteeing each of the one-way delays. However, the solution to reduce the one-way delays to guarantee the round-trip delay has its drawbacks. The major issue is that it can not take full advantage of the allowed round trip delay limitation.
There is thus a general need for an improved strategy for reducing and/or handling round-trip delay in communication systems.